Sporocarps scattered, individual or in small groups of 2-10, sessile,
pulvinate with circular or somewhat irregular circumscription, with
constricted base. Up to ca. 1 mm Ø.
Hypothallus inconspicuos, membranous and often with ochraceous lime
scales as peridium.
Peridium brownish grey in RL, with scattered, ocraceous stellate
lime scales. In TL thin, membranous, hyline, with irregular, bright
Capillitium of thin, almost hyaline to pale brownish threads,
± parallel, wavy and with many transverse connections, hardly
expanded at nodes.
Spores globos or slightly ellipsoid, dark brown in RL, medium greyish
brown in TL, with ± regularly distributed, medium sized short spines,
9-9.74-10.5 µm Ø (n=25).
On underside of leaf of Petasites hybridus.
Only one location is known at present: Copenhagen, Fælledparken.
Being described only recently the global distribution is not known,
but it seems likely that Didymium vernum is widespread in Europe,
following the host, to which it apparently is restricted.
Kuhnt, Baumann and Nowotny mentions finds from Germany and France.
Further it is known from The Netherlands (Hooff, pers. com.) and
Denmark. Additional finds from Germany have been reported in the
internet forum Pilzforum.eu
Didymium vernum Kuhnt, K. Baumann & Nowotny was desribed in a paper by
Kuhnt, Andreas; Baumann,
Karlheinz & Wolfgang Nowotny
in the spring of 2014 along with the
revitalization of Didymium tussilaginis (Berk. & Broome) Massee.
I am grateful to Hans van Hooff for making me aware of this paper,
which inspired me to search for the two species in Denmark - with success.
Despite the fact that only one locality in Denmark for Didymium vernum
is known at present, there is reason to believe that it is widespread,
although not as common as Didymium tussilaginis, which occurs in the
The description and discussion is based on one Danish collection: hfg 2427.
Abbreviations: TL : transmitted light; RL : reflected light; Ø : diameter;
TBU : Danish Botanical Topographical District.
Colour-codes refer to: Kornerup, A. & J. H. Wanscher 1974: Farver i farver.
5th reprint. Politikens Forlag, Copenhagen.
When not otherwise indicated spore measurements are given as:
min-mean-max or (extreme-)min-mean-max(-extreme). Spore measurements are exclusive of ornamentation.
Line drawings are free hand sketches.
Distribution maps: Maps of Danish distributions are based on material seen
by the author. World distributions are based on
reports extracted from literature.